Information processing systems having a voice generating capability are presently employed as answering machines, voice messaging systems, voice response units and in general as intelligent peripherals. The voice signal may be prerecorded on audio tape or may be digitized, compressed and stored, for example, on a magnetic disk.
A typical application couples the information processing system to one or more phone lines, the system detecting the occurrence of a ring signal and answering the phone. Often a standard prompt voice message is sent to the phone line. Depending on the type of system the caller may depress certain buttons on a Touch-Tone phone set in order to inform the system of a specific type of action desired by the user. For example, after hearing the initial prompt the user may depress a specific button in order to signal the system to play back any stored voice messages intended for the caller. Other more sophisticated interactions can also be accomplished. For example, the information processing system may have access to a large data base, such as a data base containing stock quotations. The caller may signal the system to access one or more quotations from the data base whereafter the system converts the quotation to an audio voice signal which is output to the caller's phone line.
As can be appreciated, for such systems the interaction between a caller and the system may become quite complex. As a relatively simple example, if the caller desires to learn if any voice messages are stored for the caller the system may respond with a voice signal such as "you have three new voice messages". In generating this response the number "three" is a variable which is determinable at the time that the caller is connected to the system. Furthermore, the word "messages" is also a variable in that if only one voice message is pending the singular form "message" should be returned and not the plural form.
It can thus be appreciated that the ability to accurately define a series of system responses to an incoming call is an important aspect of such a voice response system. Also, it is preferable that a voice applications writer be able to create and modify the system responses in a relatively uncomplicated and time efficient manner. That is, the operator of the system should be able to interact with the voice response system to create and modify voice responses in a manner which does not require the direct assistance of the provider of the system or the direct assistance of skilled programming personnel.